Preparation of liquid-crystal compounds

ABSTRACT

There is disclosed the preparation of liquid-crystal compounds of the structure:   WHERE X IS AN INTEGER OF 0 TO 10 AND Y IS THE SAME OR DIFFERENT INTEGER OF 1 TO 10. The compounds are prepared by the reaction of para-n-alkylaniline and para-n-alkenyloxybenzaldehyde.

ssarwssc 5?? RR 3 97 253 e681 United State Dietrich et al.

[ PREPARATION OF LIQUID-CRYSTAL I COMPOUNDS [75] Inventors: Heinz J. Dietrich; Edward L. Steiger,

both of Toledo, Ohio [73] Assignee: Owens-Illinois, Toledo, Ohio [22] Filed: May 18, 1971 [21] Appl. No.: 144,671

OTHER PUBLICATIONS Rudolph Gabler of Leipzig, Inaugural-Dissertation (1939) Kelher et al. Angewandte Chemie, 22, 903-904 I969) 451 July 3,1973

Weygand, 2. Physik Chemie, Vol. 53 pp. 75-77 I942) Primary Examiner-Leon Zitver Assistant Examiner-Gerald A. Schwartz Attorney-Donald K. Wedding and E. J. Holler 5 7 ABSTRACT There is disclosed the preparation of liquid-crystal compounds of the structure:

where x is an integer ofO to 10 and y is the same or different integer of I to 10. The compounds are prepared by the reaction of para-n-alkylaniline and para-nalkenyloxybenzaldehyde.

3 Claims, No Drawings PREPARATION OF LIQUID-CRYSTAL vention are commercially available. Both may be typi- COMPOUNDS cally used without further purification.

This invention relates to the preparation ofmesomor- Schiff bases are prepared by refluxing equimolar phic compounds. More particularly, this invention requantities of the p-substituted benzaldehyde and anilates to the preparation of mesomorphic compounds 5 line in anhydrous ethanol for about 4 to '6 hours. The which may be utilized in display type devices. solvent and water are removed and the residue recrys- Mesomorphic materials, typically referred to as liqtallized several times from ethanol until the transition uid-crystal materials, are organic compounds in a trantemperatures remain constant. The crude yields ranged sition state between crystalline solid and normal isotrofrom 70 to 90 percent. The infra-red spectra show a strpic liquid forms. Such materials are well known in the ong band at 1,629 cm corresponding to the carbon prior art. Likewise, it is known in the prior art to use nitrogen double bond in Schiff base compounds. Other such liquid-crystal materials in display type devices. absorptions are compatible with the expected struc- In accordance with this invention, there is prepared tures. I liquid-crystal compounds of the structure: Transition temperatures are determined on a Leitz where x is an integer of 0 to 10, preferably 0 to 5, and Ortholux polarizing microscope using a Mettler FP-2 y is the same of different integer of 1 to 10, preferably heating stage.

I to 5, by the reaction of para-n-alkylaniline, N(para-allyloxybenxylidene)para-n-butylaniline ll-,-N Q: 0 -u(' ll-:.v|1.

and para-n-alkenyloxybenzaldehyde, (where x is 0 in the basic structure) was prepared in accordance with this invention. The structure was ana- I j lyzed at 8l.70 percent by weight carbon, 7.93 percent (0112)*Ihmmmo O by weight hydrogen, and 4.89 percent by weight nitrogen compared with calculated theoretical analysis values of 8 l .87 percent by weight carbon, 7.90 percent by where x and y are as defined above. weight hydrogen, and 4.77 percent by weight nitrogen.

The para-n alkenyloxybenzaldehydes of this inven- The compound changed from the crystalline to the netion are prepared by a first reaction of paramatic phase at 49.7 C and from nematic toflisotropic hydroxybenzaldehyde and potassium hydroxide in a diat 68.5 C.

methyl formamide-benzene (1:1) solvent mixture, re- N(para-crotyloxybenzylidene)para-n-butylaniline fluxing at about 100 C to remove the water of reaction (where x is l in the basic structure) was prepared in acazeotropically, and reacting the product of the first recordance with this invention. The structure was anaaction with an appropriate alkenyl halide. The solution lyzed at 82.28 percent by weight carbon, 8.24 percent is then heated to reflux for about 4 to 6 hours. After the by weight hydrogen, and 4.67 percent by weight nitrosolvents are removed in vacuum, the products are sepa- 40 gen compared with calculated theoretical analysis valratedfrom the inorganic residues by a water immiscible ues of 82.04 percent by weight carbon, 8.19 percent by solvent followed by fractionation to recover the reweight hydrogen, and 4.56 percent by weight nitrogen. quired para-n-alkenyloxybenzaldehyde. The compound changed from the crystalline to'the M The following equations-are representative: matic phase at 62.7" C and from nematic to isotropic at 942 C.

The following equations are representative of the re- The liquid-crystal compounds prepared in accoraction of para-,n-alkylaniline and para-ndance with this invention maybe utilized in display dealkenyloxybenzaldehyde: vices, especially of the electronic type.

The appropriate alkenyl halides are commercially Such devices typically'comprise a thin layer of liquid available'Also the para-n-alkylanilines used in this incrystals sandwiched between twoshe'ets of glass. Noreffect is obtained by use of liquid-crystal materials of.

the nematic type.

In one particular embodiment, a liquid-crystal material is sandwiches as a dielectric in a parallel plate capacitor with one electrode transparent and the other electrode either transparent or reflecting. The liquid is kept between the electrodes by capillary action, since electrode spacings are of the order of A mil. An applied do. or low-frequency (less than 100 Hz.) field of more than 30,000 volts per centimeter changes the cell from transparent to turbulent in a few milliseconds. Depending upon the liquid-crystal composition, the opaque effect may remain even after the field is removed. In other words, an optical signal may be maintained with no applied power. The cell can be turned clear again by applying a higher-frequency (greater than 700 Hz.) signal. The sample remains clear after the signal is removed.

Additional embodiments of liquid-crystal electrooptical devices are disclosed and illustrated in U. S. letters Pat. Nos. 3,401,262 and 3,410,999; Proceedings of the IEEE, Vol. 56, No. 12, December, 1968, pages 2,l46 to 2,149; The Glass Industry, August, 1968, pages 423 to 425; Chemical and Engineering News, Sept. 30, 1968, pages 32 and 33; Physics Today, July, 1970, pages 30 to 36; Electronics, July 6, 1970, pages 64 to 70; U. S. letters Pat. No. 3,322,485 to Williams.

It is also contemplated using the liquid-crystal compounds in a charge storage display/memory device, especially multiple gas discharge display/memory panels which have an electrical memory and which are capable of producing a visual display or representation of data such as numerals, letters, television display, radar displays, binary words, etc.

Multiple gas discharge display and/or memory panels of the type with which the present invention is especially concerned are characterized by an ionizable gaseous medium, usually a mixture of at least two gases at an appropriate gas pressure, in a thin gas chamber or space between a pair of opposed dielectric charge storage members which are backed by conductor (electrode) members, the conductor members backing each dielectric member being transversely oriented to define a plurality of discrete discharge volumes and constituting a discharge unit. In some prior art panels the dischargeunits are additionally defined by surrounding or confining physical structure such as by cells or apertures in perforated glass plates and the like so as to be physically isolated relative to other units. In either case, with or without the confining physical structure, charges (electrons, ions) produced upon ionization of the gas of a selected discharge unit, when proper alternating operating potentials are applied to selected conductors thereof, are collected upon the surfaces of the dielectric at specifically defined locations and constitute an electrical field opposing the electrical field which created them so as to terminate the discharge for the remainder of the half cycle and aid in the initiation of a discharge on a succeeding opposite half cycle of applied voltage, such charges as are stored constituting an electrical memory.

Thus, the dielectric layers prevent the passage of any conductive current from the conductor members to the gaseous medium and also serve as collecting surfaces for ionized gaseous medium charges (electrons, ions) during the alternate half cycles of the AC. operating potentials, such charges collecting first on one elemental or discrete dielectric surface area and then on an opposing elemental or discrete dielectric surface area on alternate half cycles to constitute an electrical memory.

An example of a panel structure containing nonphysically isolated or open discharge units is disclosed in U. S. letters Pat. No. 3,499,167 issued to Theodore- C. Baker et al.

An example of a panel containing physically isolated units is disclosed in the article by D. L. Bitzer and H. G. Slottow entitled The Plasma Display Panel A Digitally Addressable Display with Inherent Memory, Proceeding of the Fall Joint Computer Conference, IEEE, San Francisco, California, November 1966, pages 541-547. Also reference is made to U. S. letters Pat. No. 3,559,190.

In the operation of the panel, a continuous volume of ionizable gas is confined between a pair of photoemissive dielectric surfaces backed by conductor arrays forming matrix elements. The cross conductor arrays may be orthogonally related (but any other configuration of conductor arrays may be used) to define a plurality of opposed pairs of charge storage areas on the surfaces of the dielectric bounding or confining the gas. Thus, for a conductor matrix having H rows and C columns the number of elemental volumes will be the product H X C and the number of elemental or discrete areas will be twice the number of elemental discharge volumes.

The gas is one which produces light (if visual display is an objective) and a copious supply of charges (ions and electrons) during discharge. In an open cell Baker et al. type panel, the gas pressure and the electric field are sufficient to laterally confine charges generated on discharge within elemental or discrete volumes of gas between opposed pairs of elemental or discrete dielectric areas within the perimeter of such areas, especially in a panel containing non-isolated units.

As described in the Baker et al. patent, the space between the dielectric surfaces occupied by the gas is such as to permit photons generated on discharge in a selected discrete or elemental volume of gas to pass freely through the gas space and strike surface areas of dielectric remote from the selected discrete volumes, such remote, photon struck dielectric surface areas thereby emitting electrons so as to condition other and more remote elemental volumes for discharges at a uniform applied potential.

With respect to the memory function of a given discharge panel, the allowable distance or spacing between the dielectric surfaces depends, inter alia, on the frequency of the alternating current supply, the distance typically being greater for lower frequencies.

In the practice of this invention, it is contemplated that a particular liquid crystal may be prepared and/or utilized alone or in combination with other liquidcrystal compositions of the same or different family,

e.g., such as a mixture of 2 or more compositions. This may be especially desirable since mixtures of compounds may have lower transition temperatures than the individual compounds.

We claim: 1. As a composition of matter, a compound having the chemical structure nematic phase at about 49.7 C and from nematic to isotropic at about 685 C.

3. The composition of claim 1 wherein x is l, y is 4,

and the compound changes from the crystalline to the nematic phase at about 62.7 C and from nematic to isotropic at about 942 C. 

2. The composition of claim 1 wherein x is 0, y is 4, and the compound changes from the crystalline to the nematic phase at about 49.7* C and from nematic to isotropic at about 68.5* C.
 3. The composition of claim 1 wherein x is 1, y is 4, and the compound changes from the crystalline to the nematic phase at about 62.7* C and from nematic to isotropic at about 94.2* C. 